Device for Seat Tilt Adjustment of a Chair

ABSTRACT

A device is provided for seat tilt adjustment of a chair, in particular an office chair. To provide seat tilt adjustment, which enables a particularly safe and reliable adjustment of the seat tilt, the device encompasses a base support, a seat support connected to the base support by use of a joint as well as an adjustment mechanism, which allows a selectively forward pivot movement of the seat support beyond a substantially horizontal base position.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuing application, under 35 U.S.C. § 120, of copending International application PCT/EP2006/003068, filed Apr. 5, 2006, which designated the United States; this application also claims the priority, under 35 U.S.C. § 119, of German patent application DE 10 2005 017 143.5, filed Apr. 13, 2005; the prior applications are herewith incorporated by reference in their entirety

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to a device for seat tilt adjustment (seat angle adjustment) of a chair, in particular an office chair.

High-quality office chairs are often equipped with a so-called synchronous mechanism, by which the seat and the backrest of the chair pivot together in a backwards and downwards movement in response to a reclining of the user in a correlated movement. Furthermore, different adjustment possibilities are known for improving the ergonomics of office chairs, such as, for example, the height adjustment of the seat, backrest and armrest, the adjustability of the armrest in longitudinal and lateral position as well as the longitudinal adjustment of the chair.

Furthermore, to further improve the ergonomics of office chairs, an adjustability of the base angle of the chair is called for to an increased extent. It should thereby at least be possible to adjust the seat between a horizontal position and a position, which is inclined slightly forwards. In response to the activation of the synchronous mechanism, the backwards downwards pivot movement of the chair, caused with it, is thus carried out from this position.

BRIEF SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide a device for seat tilt adjustment of a chair that overcomes the above-mentioned disadvantages of the prior art devices of this general type, which enables a particularly safe and reliable adjustment of the seat tilt.

With the foregoing and other objects in view there is provided, in accordance with the invention, a device for seat tilt adjustment of a chair, preferably an office chair. The device contains a base support, a joint, a seat support connected to the base support by the joint, and an adjustment mechanism allowing a selectively forward pivot movement of the seat support beyond a substantially horizontal base position.

It is a basic idea of the invention to pivot the seat support itself beyond its base position so as to adjust the seat tilt of the chair. The adjustment of the seat tilt may selectively either be turned on or off. This enables a particularly flexible handling, depending on the use and user request. Furthermore, the device as claimed in the invention can optionally be installed into an otherwise conventional synchronous mechanism. In other words, a refitting may be selected.

In accordance with an added feature of the invention, the joint is a swivel-slide joint. The joint includes a sliding element connected to the seat support and a sliding guide connected to the base support. The sliding element is disposed in the sliding guide.

In accordance with a further feature of the invention, the adjustment mechanism is configured such that an operation of the adjustment mechanism effects a change of a displacement path of the seat support in the joint. Preferably, the adjustment mechanism is part of the seat support. The adjustment mechanism has at least one adjustable stop element. The at least one adjustable stop element is configured for stopping against the base support. The adjustment mechanism contains a wedge gear for operating the at least one adjustable stop element. The wedge gear has a driving wedge and the adjustment mechanism includes an operating element and a spring element, the spring element is operated by the operating element for moving the driving wedge of the wedge gear. The spring element may be operated without causing an adjustment of the at least one adjustable stop element as long as a pressure is put on the seat support.

In accordance with an additional feature of the invention, the at least one adjustable stop element is configured for stopping against the sliding guide of the base support.

Other features which are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is illustrated and described herein as embodied in a device for seat tilt adjustment of a chair, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a diagrammatic, perspective view of a synchronous mechanism in a horizontal base position according to the invention;

FIG. 2 is a side view of the synchronous mechanism;

FIG. 3 is a side view of the synchronous mechanism in an angled position;

FIG. 4 is a perspective, exploded view of an adjustment mechanism;

FIG. 5 is a top view onto the adjustment mechanism, set up for the angled position;

FIG. 6 is a top view onto the adjustment mechanism, set up for a base position; and

FIG. 7 is a sectional view taken along the line VII-VII shown in FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is shown an exemplary synchronous mechanism 1, that is, a component in the underframe of an office chair, which ensures a mutually coupled kinematics, which entails a certain relative movement of the seat and backrest to one another. For this purpose, a base support 2 is placed on a non-illustrated chair supporting post, on which the base support 2 is mounted, on the one hand, a seat support 3, which is pivotable about a lateral axis and which is connected to the base support 2 in an articulated manner and, on the other hand, a backrest support 4, which is also pivotable about a lateral axis and which is connected to the base support 2 in an articulated manner.

The seat of the office chair, which is, as a general rule, provided with a padded seat, is mounted on the seat support 3 (not illustrated herein for reasons of clarity). For this purpose, provision is made on the lateral frame elements 5 of the substantially frame-shaped seat support 3 for a number of latches 7, which are disposed behind one another in a longitudinal direction 6 of the chair, the latches 7 serving the purpose of positioning and fastening the seat on the seat support 3 in an inherent manner, which is not explained in detail.

The backrest support 4, which extends backwards in an established manner from the actual synchronous mechanism 1, supports the backrest of the office chair at a non-illustrated arm, which runs upwards. Flanges 8, 9 of the backrest support 4, which is substantially bifurcate in the top view, are disposed at both sides of the base support 2.

The seat support 3 and the backrest support 4 are coupled in an articulated manner such that a backwards pivoting movement of the backrest—as it can be caused by a leaning of the user against the backrest, for example—induces a lowering movement of the trailing edge of the seat. This correlated seat-backrest-movement entails a considerable comfort advantage and is desirable for orthopedic reasons. Provision is made on both sides of the base support 2 for operating levers 10, 11, which serve the purpose of triggering the height adjustment of the chair supporting post and for operating the pivoting mechanism, respectively.

The further set-up of the synchronous mechanism 1, in particular the connection of the seat support 3 and of the base support 2 via a guide configuration or the like for providing the correlated seat/backrest movement will not be further considered in the following.

For better understanding, however, it is pointed out that the seat support 3, at its front end region 12, is connected to the base support 2 via two swivel-slide joints 13. See FIG. 7, in which one of the swivel-slide joints 13 is illustrated in a section. On the one hand, each swivel-slide joint 13 is made up of a sliding element 14 connected to the seat support 3, which, on the other hand, is encompassed in a sliding guide, which is formed by two mutually spaced apart sliding flanges 15, 16, which are fixedly connected to the base support 2. In the illustrated horizontal base position, the upper sliding flange 15 stops at a stop element 17 at the seat support 3, which will be explained below in more detail. Through this, it is avoided that the seat support 3 completes a forwards pivoting movement, which extends beyond the substantially horizontal base position. Both sliding flanges 15, 16 encompass convex guide surfaces, which permit the sliding element 14 and thus also the seat support 3 connected to the sliding element 14 to follow the pivoting movement backwards downwards. In other words, the sliding element 14 of the seat support 3, which is configure according to the type of a rail, moves with its upper side and its lower side along the guide surfaces of the upper and lower sliding flanges 15, 16, wherein the sliding element 14, in any pivoting state between upper and lower sliding flange 15, 16, is guided in a particularly safe manner. Other types of joints can also be used.

An adjustment mechanism 18 as claimed in the invention is assigned to the seat support 3. As will be explained in more detail below, the adjustment mechanism 18 enables a safe and reliable adjustment of the seat tilt. An operating lever 19, which is disposed laterally at the synchronous mechanism 1 in the same way as the remaining operating levers 10, 11 and which can be operated by being removed and inserted in an operating direction 20, respectively, is arranged for operating the adjustment mechanism 18.

In the exemplary embodiment, a forward incline of the seat support 3 about an angle α of approximately 3 degrees is possible by an adjustment of the seat tilt. Due to the seat/backrest correlation, this corresponds here to a deviation of the backrest about an angle β of approximately 8 degrees; see FIG. 3. These angle designations are only exemplary and serve the purpose of clarifying the functionality. In particular, they depend on the length of the stop elements 17 in the adjustment mechanism 18 and on the available displacement path, respectively, as well as on the concrete configuration of the synchronous mechanism 1.

Based on the “retracted” position of the adjustment mechanism 18 illustrated in FIG. 5, which corresponds to an angle position of the seat support 3 (as illustrated in FIG. 3), the function thereof is explained below. In the position of the adjustment mechanism 18 illustrated here, the seat support 3 can be inclined forwards beyond its horizontal base position.

The adjustment mechanism 18 is substantially made up of a base plate 21, on which the actual elements of the mechanics are mounted, as well as of a cover plate 22. In the final mounted state, the base plate 21 of the adjustment mechanism 18 is covered by the cover plate 22, which is fastened to the base plate 21 by screws 23.

The adjustment mechanism 18 contains two prism-shaped stop elements 17, 17′, which are encompassed in guide channels 24 of the adjustment mechanism 18, which extend in longitudinal direction 6. At lower sides 59 of the stop elements 17, 17′, provision is made for non-illustrated detent openings, which, when in “retracted” state, cooperate with detent knobs 60, which are disposed in the guide channels 24. The position of the stop elements 17, 17′ in this state is additionally secured through this.

Double T-shaped cushioning elements 25, which are made up of a softer plastic material, for example rubber, are inserted in the stop elements 17, 17′, which are made up of a plastic material. Front sides 26 of the stop elements 17 are completely covered by the cushioning elements 25. On their back sides 27, the stop elements 17 encompass slanted contact surfaces 28, which are oriented towards one another and in the direction to the center of the adjustment mechanism 18. In the “retracted” position shown herein, two angled wedge elements 29, 30 containing wedge surfaces 31 being mounted thereon at the outer ends, which face away from one another, rest against the contact surfaces 28 of the stop elements 17. The wedge elements 29, 30, in turn, are located in guide channels 33 of the adjustment mechanism 18, the guide channels 33 extending substantially in lateral direction 32 extending perpendicular to the longitudinal direction 6 and being connected with one another by a coupling mechanism 34, which will be described below in more detail.

One of the wedge elements 29 encompasses a recess 35, which is provided with slanting sidewalls and which serves as the support for one end 42 of a substantially L-shaped steel spring 36. The bent end 42 of the steel spring 36 is thereby inserted into an opening of the wedge element 29 and is fixed therein so as to be rotatable.

The steel spring 36 is connected with the operating lever 19. The operating lever 19 is configured so as to be made up of two parts and is formed substantially of an operating arm 37, which is curved so as to be slightly S-shaped and at the end of which an operating knob 38 is mounted and an operating slide 39 fixed on the operating arm by screws 23 in which the other end 40 of the steel spring 36 is fastened. For this purpose, the operating slide, similarly to the wedge element 29, encompasses an opening 41, into which the bent other end 40 of the steel spring 36 is inserted. The steel spring 36 is encompassed in a bifurcate guide element 43 at the operating slide 39, which, at the same time, serves as an anti-twist device. The operating slide 39 is guided in a lateral direction 58 in the base plate 21 of the adjustment mechanism 18.

The operating slide 39 encompasses a central opening 44, in which a catch element 45 is disposed. The catch element 45 serves the purpose of locking the adjustment of the seat angle in the horizontal base position and in the angle position, respectively, and is configured in such a manner that it interacts so as to catch with two correspondingly provided catch recesses 46, 47, which are disposed in the base plate 21 of the adjustment mechanism 18, see FIG. 4. When locked in place, the catch element 45 can be disengaged, in each case, by a simple operation of the operating element 19.

In response to an operation of the operating element 19 in operating direction 20 towards the seat support 3, a movement of the steel spring 36 occurs in operating direction 20, wherein the one wedge element 29 is carried along. The wedge element 29, which, at its end facing the one stop element 17, encompasses a wedge surface 31, serves as an impellent wedge of a wedge gear and displaces the stop element 17, which now assumes the function of a driven component, perpendicular to the operating direction 20 in longitudinal direction 6. In other words, the stop element 17 is displaced in its guide channel 24 by the wedge element 29, which is disposed perpendicular thereto. Preferably, the wedge angle is 45 degrees. The displacement of the stop element 17 shortens the displacement path of the seat support 3, which is still available, by an amount, which corresponds to the width 48 of the outer ends of the wedge elements 29, 30. The corresponding position of the adjustment mechanism 18 is shown in FIG. 6. In other words, once the horizontal base position is reached, the stop element 17 rests against the upper flange 15 of the swivel-slide joint 13. A further displacement beyond this base position and thus a lowering the seat support 3 is then no longer possible. The seat support 3 is in its horizontal base position, as illustrated in FIG. 2.

For a particularly safe function of the adjustment mechanism 18, provision is made for the use of two stop elements 17, 17′ so that a stop against the corresponding sliding guides 15 occurs for both swivel-slide joints 13 of the seat support 3. For this purpose, the wedge element 17, which is directly impinged upon by the steel spring 36, is coupled with a second wedge element 30, which impinges upon the opposite stop element 17′ in the same manner. For this purpose, a movement of the opposite wedge element 30 in opposition to the original operating direction 20 is required. In order to achieve this, a deflection of the movement occurs by a guide element 49, which is located on the base plate 21 of the adjustment mechanism 18 so as to be rotatable and which serves as a type of bridge. For this purpose, the guide element 49 encompasses, in its center, a bearing opening 61 for accommodating a pivot pin 62, which is mounted on the base plate 21 of the adjustment mechanism 18. At their ends located opposite the wedge surfaces 31, the two wedge elements 29, 30 encompass journals 50, which extend perpendicular to the operating direction 20 and which project into the long holes 51 of the guide element 49 and thus enable a mechanical coupling. In other words, the coupling of the two wedge elements 29, 30 is carried out by an indirect crank mechanism. To achieve a particularly safe guide of the wedge elements 29, 30, they encompass, at their lower side, a spring 52, which is encompassed in a corresponding groove 53 in the base plate 21 of the adjustment mechanism 18, see FIG. 7.

If the stop elements 17, 17′ are in the “extended” position, which corresponds to a horizontal base position of the seat support 3, the rear sides 27 of the stop elements 17, 17′ then rest against the front sides 54 of the wedge elements 29, 30, see FIG. 6. If pressure is put on the seat support 3, for example in that a user sits on the chair and puts pressure on the seat in the direction of the front end region 12, without supporting himself on the backrest, forces act on the stop elements 17, 17′ in longitudinal direction 6, which cause a jamming of the wedge elements 29, 30 between the rear sides 27 of the stop elements 17, 17′ on the one hand and the opposite shoulders 55 of the guide channel 33, on the other hand. If, in this situation, the operating element 19 is operated, that is, the steel spring 36 is retrieved into its starting position, which is shown in FIG. 5, a L-journal 56 of the steel spring 36 fastened to the operating slide 39 is already in the position shown in FIG. 5, while the other L-journal 57 still remains with its journal end 42 in the position illustrated in FIG. 6. In this situation, the two L-journals 56, 57 form an obtuse angle between one another. The steel spring 36 is prestressed.

As soon as the seat support 3 is relieved of pressure, for example when the user stands up or leans against the backrest, the second L-journal 57 abruptly follows the first L-journal 56 and causes the movement of the wedge elements 29, into the position shown in FIG. 5, whereby the stop elements 17, 17′ can retract. This safety feature ensures that a sudden change of the adjustment of the angle is not possible. The transition from the one position into the other position always requires a “pressure relief” of the seat support 3.

This also holds true in the reverse case. If the seat support 3 is in the angle position (FIG. 5) and if pressure is put on the chair, the operating lever 19 can still be operated. In this case, the occurring forces cause a clamping of the rear sides 27 of the stop elements 17, 17′ directly on the opposite sides 55 of the guide channels 33. The first L-journal 56 of the steel spring 36 is then already in the position illustrated in FIG. 6, while the second L-journal 57 is still in the position illustrated in FIG. 5. In other words, the L-journals 56, 57 form an acute angle. The steel spring 36 is prestressed.

In response to a pressure relief of the seat, an abrupt displacement of the wedge elements 29, 30 then occurs by the steel spring 36, which leads to an extension of the stop elements 17, 17′. As a result of these safety features, the operating element 19 is always slightly movable. At the same time, an adjustment takes place only if the seat is relieved of pressure, that is, never offhand. 

1. A device for seat tilt adjustment of a chair, the device comprising: a base support; a joint; a seat support connected to said base support by said joint; and an adjustment mechanism allowing a selectively forward pivot movement of said seat support beyond a substantially horizontal base position.
 2. The device according to claim 1, wherein said joint is a swivel-slide joint.
 3. The device according to claim 2, wherein said joint includes a sliding element connected to said seat support and a sliding guide connected to said base support, said sliding element is disposed in said sliding guide.
 4. The device according to claim 1, wherein said adjustment mechanism is configured such that an operation of said adjustment mechanism effects a change of a displacement path of said seat support in said joint.
 5. The device according to claim 1, wherein said adjustment mechanism is part of said seat support.
 6. The device according to claim 1, wherein said adjustment mechanism has at least one adjustable stop element.
 7. The device according to claim 6, wherein said at least one adjustable stop element is configured for stopping against said base support.
 8. The device according to claim 6, wherein said adjustment mechanism contains a wedge gear for operating said at least one adjustable stop element.
 9. The device according to claim 8, wherein: said wedge gear has a driving wedge; and said adjustment mechanism includes an operating element and a spring element, said spring element being operated by said operating element for moving said driving wedge of said wedge gear.
 10. The device according to claim 9, wherein said spring element may be operated without causing an adjustment of said at least one adjustable stop element as long as a pressure is put on said seat support.
 11. The device according to claim 1, wherein the chair is an office chair.
 12. The device according to claim 6, wherein said at least one adjustable stop element is configured for stopping against said sliding guide of said base support. 